The present invention generally relates to loudspeaker rigging systems and more particularly to rigging hardware for suspending a stacked array of loudspeakers of a sound reinforcement system at a predetermined location relative to an audience. The present invention has particular application in rigging a stacked array of loudspeakers wherein a vertical splay between loudspeakers is desired to achieve a desired coverage and acoustic performance.
Sound systems for large venues typically involve the suspension or xe2x80x9cflyingxe2x80x9d of stacks of loudspeaker in vertical arrays to achieve the necessary acoustic output and coverage for a large audience. Such vertical stacks of loudspeakers are typically suspended and held together by rigging systems which can be attached to rigging hoists which position the stack at a desired elevation and location, typically above or in the vicinity of a performance stage. A flown stack of loudspeakers can include many speaker boxes and the rigging system for flying the stack must be strong enough to support the enormous weight of a large stack. Such rigging systems generally involve the use of metal framing elements secured to the speaker boxes that can be used to link the speakers together in a stacked arrangement and to lift the stack to an overhead flying position.
Often the design requirements of a sound reinforcement system and loudspeaker specifications will require that the individual speaker boxes in a vertical stack of loudspeakers be angled relative to each other so as to create a stack having a vertical splay. Setting the proper splay angle can be critical to achieving desired acoustic performance and minimizing interference between the acoustic output between speakers in the stack. Splay angles, that is the angular separation of the speakers, are provided by adjusting the linkage lengths between rigging the frames of the stacked speakers to create a desired angle. One existing approach for accomplishing this is to provide a relatively long chain linkage at the front corners of the speakers while providing a short link at the back of the speakers. When the speakers are hoisted overhead to their flown position, a pull back is used to pull the front corners of the speakers apart to the extent allowed by the chain linkages. The drawback with pull backs is that they greatly increase the difficulty of the installation, particularly when the speaker stack includes a large number of speakers. With a large stack, separation between the topmost speakers in the stack can only be accomplished by pulling back on the speakers beneath which often can only be accomplished with great difficulty.
Another known approach to creating a desired splay angle is to use straight, rigid and relatively long extension bars to link the front or rear corners of the speaker""s rigging frames. Such extension bars have locator holes distributed along their length for achieving different separations between the speaker corners, and can be exchanged with other extension bars with shifted locator holes such that one bar can be used to achieve intermediate splay angles provided by another bar. One problem with such extension bars is that they are often misplaced or lost, and are cumbersome to install. Another difficulty is that the degree of adjustment of the splay angle for any given bar is inherently limited by the size and separation of their locator holes necessary to maintain component strength.
The present invention provides a rigging system for loudspeakers which overcomes the disadvantages of prior art rigging systems. The rigging system of the present invention not only provides for relative ease in the assembly and flying of a vertical stack of loudspeakers, it also permits fine adjustments of the splay angles of the loudspeakers without the need to exchange parts. The present invention also provides a rigging system which holds the separation between speaker boxes in both tension and compression and thereby eliminates the need for pulling back of a flown vertical stack of loudspeakers.
Briefly, the invention involves a rigging system and hardware for flying a vertical stack of speakers which includes a rigging side frame which is interconnectable with the rigging side frames of other speakers in the stack. A rigging system in accordance with the invention will provide for a left and right rigging side frame for the left and right sides of a speaker cabinet. By fixing the rigging side frames of the invention to the sides of the loudspeaker cabinets, the loudspeakers can be interconnected and splayed at precise splay angles required by the acoustic output characteristics of the loudspeakers without exchanging parts. In accordance with one aspect of the invention, all the elements that link the rigging side frames together are held captive in the rigging side frames such that installers do not have to handle separate linkage elements that can become temporarily misplaced or lost resulting in increased set-up time.
The rigging side frame of the invention includes a rigid frame structure, suitably manufactured of steel tubing, which has a top end, bottom end, and front and rear corners, and which is mountable to the side of a correspondingly sized loudspeaker. The side frame further includes a rear link for pivotally linking the a rear corner of a rigging frame of one loudspeaker to a rear corner of a same side rigging frame of another loudspeaker placed in stacked relation therewith such that the corners of the stacked loudspeakers are joined in a manner that permits the loudspeakers to be pivotally splayed about their rear corners. A cam plate link is pivotally attached to a cam pivot at one of the top and bottom ends of the frame structure in displaced relation to the rear link. Preferably, it is located at or near a front corner of the framed structure to achieve maximum horizontal displacement between the rear link and cam plate. However, it is contemplated that the cam plate can be located inboard the front of the frame structure and still be within the scope of the invention. Also, in the preferred embodiment the rear link and cam plate are located at opposite corners of the frame structure with the preferred location of the rear link being the top rear corner of the frame and the preferred location of the cam plate being the bottom front corner of the frame to permit the cam plate to drop down from the frame by gravity. However, other locations of the rear link and cam plate are possible within the scope of the invention, such as locating both the rear link and cam plate link on either the top or bottom corners of the frame, or placing the rear link on the bottom and the cam plate link on the top.
The cam plate link has at least two, and preferably multiple link openings displaced at different angles about the cam pivot point and falling on different radii relative to the cam pivot point. Each rigging side frame has a cam plate attachment structure on the end of the frame structure opposite the cam plate link for receiving cam plate links of the rigging side frames of adjacent loudspeakers in the stack. Thus, where the cam plate link is provided at the bottom front corner of the frame structure, the corresponding cam plate attachment structure is provided at the top front corner of the frame structure for receiving cam plate links which are pivotally dropped down from the bottom corner of the rigging side frame of the loudspeaker above. The cam plate attachment structure provides for attaching to one of the link openings of the cam plate link of an adjacent frame, suitably by a pin which inserts through the cam plate structure and cam plate link to lock the cam plate of one frame to the frame structure of an adjacent frame. The splay of the speakers is set by selecting an link opening on the cam plate link having a suitable radial distance from the cam plate""s cam pivot point. The distance between the pivot point and the selected link opening of the cam plate will set the separation of the rigging side frames, and hence the loudspeakers, at the location of the cam plate link. As the loudspeakers are separated, the rear corners of the side frames, and hence the loudspeakers, will be held together by the rear link of the side frames.
In another aspect of the invention, the frame structure of the rigging side frames have stow away cavity areas which permit the rear links and cam plate to be retracted to a stowed position when not in use. Suitable pin openings can be provided in the frame structure for pinning the rear link and cam plate link in their stowed positions.